The present invention relates to a power source supply system for electronic equipment such as an electronic wristwatch using electric cells as the power source.
Electronic wristwatches and electronic compact calculators having electric cells as power sources have recently become available which include heavy load circuits which greatly reduce the voltage of the electric cells when operated, such as an illumination lamp for illuminating a display part, a speaker for an alarm sound, a buzzer, etc. However, with such equipment with an electric cell which drives such a heavy load circuit, the electric cell voltage is reduced by driving the heavy load circuit, frequently resulting in erroneous operation of the electronic circuit. In order to prevent erroneous operation of the electronic circuit, it is possible in advance to set the voltage level supplied to the electronic circuit to be high so that the voltage level, even after it is reduced by driving the heavy load circuit, may not become lower than the minimum voltage required for driving the electronic circuit. However, when the voltage to be supplied to the electronic circuit is set at a high level, a voltage of a level which is higher than the required level is supplied to the electronic circuit when the heavy load circuit is not in operation, so that extra power is consumed and the service life of the electric cell is unnecessarily shortened.
When two quartz oscillators or a quartz oscillator of 4 MHz band is used for attaining higher precision in the watch, the power consumption of the quartz oscillator and the divider become great, so that a power source supply system has been desired which is capable of providing a minimum voltage for driving the electronic circuit when the heavy load circuit is not in operation and providing a high voltage to the electronic circuit which prevents erroneous operation thereof when the heavy load circuit is in operation.
The present invention has been made to overcome these problems and has for its object to provide a power source supply system which enables power savings and longer service life of the electric cell.
It is another object of the present invention to provide a power source supply system which prevents erroneous operation or interruption of operation of the electronic circuit when the heavy load circuit operates.